The present invention relates to a new copper-based alloy, or rather one containing more than 90% by weight of copper, particularly adapted for the construction of components for the electronics industry thanks to its mechanical and electrical characteristics. It is known that numerous electronic components which are heavily stressed both mechanically and thermally, such as parts of switches, "lead frames" (that is the frames which support the semi-conductor plates constituting microprocessors and/or memory elements) serial bus terminal support plates, thermostat contacts and the like have to be made with alloys having, simultaneously, high ductility, high durability and mechanical strength, and high thermal and electrical conductivity; today there exist on the market very many copper-based alloys which, however, all have the inconvenience of being adapted only to a specific application for which they have been appropriately developed, and consequently each is only suitable for the construction of one or a few of the above-listed components, which is entirely unsatisfactory. Moreover, a large number of such alloys contain cadmium so that their manufacture involves heavy environmental pollution; moreover, the majority of such alloys are expensive, either because of the particularly rare elements used or, above all, because of the difficult processes for obtaining these, which require an accurate deoxidation preferably effected by means of accurate proportioning of particular deoxidising components. It is in fact known that very small percentages of oxygen drastically lower the thermal and electrical conductivity of such alloys and, above all, make soldering them impossible because of reactions which lead to hydrogen embrittlement; it is also known that, on the other hand, the addition of deoxidising elements having a high affinity for oxygen, such as phosphorus, involves the problem of accurately proportioning the content of these in dependence on the anticipated oxygen content if a drastic reduction in the conductivity by formation of solid solutions and/or phosphates is to be avoided. U.S. Pat. No. 3,677,745 resolves this latter problem in an economic manner by means of the addition of small percentages of magnesium to the alloy; this element combines with the excess phosphorus forming an intermetallic compound; this drastically limits the quantity of free P and/or Mg in the matrix and therefore avoids a drop in the conductivity even in the presence of imprecise proportions of P; moreover the intermetallic compound which forms renders the alloy subject to age-hardening by precipitation which improves its mechanical characteristics. However, the alloy the subject of the said U.S. Patent simply shifts the problem of the correct proportions from the P to the Mg, with the single advantage that the limits between which the proportion of magnesium can vary with respect to the stoichiometric proportion without detrimentally affecting the conductivity are very much wider than those of the P and can be further widened by also adding to the alloy silver (up to 0.2%) or cadmium (up to 2 %). These further additions, always present in alloys produced commercially on the basis of the Patent, evidently involve the disadvantages of high cost of primary materials and the above-mentioned risk of pollution. Moreover, alloys according to U.S. Pat. No. 3,677,745 do not resolve the technical problem of making available an alloy adapted to different uses in the electronic components field; for this reason users of alloys known today must, for each type of component to be produced (lead frame, contact, etc.) arrange to store an alloy of particular chemical composition, different from that of the alloys utilised for other components. This evidently involves the impossibility of effecting economies of scale and complicates the management of production and supplies.